The present technology relates to an automatic gain control apparatus, an automatic gain control method, and a receiver, and in particular to an automatic gain control apparatus, an automatic gain control method, and a receiver by which the gain control speed can be further increased.
In a transmission and reception system for communication/broadcasting and the like, there is known an automatic gain control apparatus (AGC) that controls a variable gain amplifier based on observed reception signal information for adjusting the level of a signal input into a signal processor of a receiver to fall in a predetermined range.
As one of the automatic gain control apparatuses, there is an automatic gain control apparatus including an over-range detection circuit that judges whether or not a voltage of an input signal input into an analog/digital (A/D) converter at a previous stage, for example, exceeds a threshold determined based on an allowable maximum voltage or the like of the A/D converter. If the over-range detection circuit judges that the voltage of the input signal exceeds the threshold determined based on the allowable maximum voltage or the like of the A/D converter, the automatic gain control apparatus changes the gain by a larger step in comparison with the normal gain control. For example, typically, the automatic gain control apparatus halves the gain.
One of the over-range detection circuits compares an average signal power of a signal input into an A/D converter with a threshold, to thereby detect an over-range (for example, see Japanese Patent Application Laid-open No. 2002-247121 (hereinafter, referred to as Patent Document 1)).
Further, another one of the over-range detection circuits compares an absolute value of the signal level of a signal input into an A/D converter, to thereby detect an over-range (for example, see PCT International Publication No. WO2008/139672, Japanese Patent Application Laid-open No. 2012-175687, and Japanese Patent Application Laid-open No. 2002-290176 (hereinafter, referred to as Patent Documents 2 to 4).